Patent GB-872391-A (GB)
Title: A continuous process for the production of "beer"
IPC: C12C11/00
Filed: 1957-07-26
Abstract: 872,391. Continuous beer fermentation. DOMINION BREWERIES Ltd. July 26, 1957 [Aug. 6, 1956; Aug. 17, 1956; Jan. 29, 1957; Feb. 22, 1957; March 22, 1957], No. 23785/57. Class 14 (2). In a continuous process for the production of a " matured beer " (i.e. without the necessity for any subsequent storage period involving maturation), fresh wort is added to a, or to a first, fermenting and maturing zone containing wort which is being continuously fermented by yeast suspended therein and agitated sufficiently to maintain the suspension in a homogeneous state and at uniform temperature, beer being withdrawn from the, or from the last fermenting and maturing zone, and there is maintained in the zone(s) a concentration of suspended yeast which is sufficient to achieve by the fermentation of the wort a desired reduction of the specific gravity of the added wort and a condition of yeast activity such that the beer produced is a " matured beer.'.' Specifications 872,392, 872,393, 872,394, 872,395, 872,396, 872,397, 872,398, 872,399 and 872,400 and divided out of the present Specification have identical subject-matter but claim other aspects of continuous beer fermentation not necessarily restricted to obtaining a "matured beer." Temperatures from 38‹ F. up to the thermal death-point of the yeast, but preferably 55‹ to 75‹ F., are employed together with high yeast concentrations (i.e. above those normally obtaining at the peak of a conventional batch fermentation), of 10 to 100 grams of yeast having a moisture content of 80% by weight, per litre of wort, preferably 25 to 35 grams per litre. It is stated that the accelerated fermentation and maturing thereby effected are achieved without any substantial danger of autolysis of the yeast. The wort to be employed may have a specific gravity which is such that dilution with up to six parts of dilutant is required for each part of entering wort. Referring firstly to Fig. 1, aerated fresh wort is continuously supplied to fermenting wort in a fermenting and maturing vessel A and the resultant beer is passed through a yeast separator B, a heat-exchanger D, in which heat may be exchanged between the outgoing fermented beer and the incoming wort, to a holding vessel E; finings and absorbent material for clarification of the beer are added through line 20 or 21. When necessary, yeast separated in the separator B may be returned to the fermenting vessel A through a return line 18. Two yeast separators may be employed alternately, B, B<SP>1</SP> (Fig. 5). The hourly rate of addition of wort is preferably one-sixtieth to one-tenth of the contents of the fermentation and maturing zone(s) for a specific gravity drop of thirty-thousandths. Two separate worts may be employed, viz. a malt wort containing strong hop flavour and a sugary wort containing the choice, delicately flavoured hops; these may be prepared in vessels F, F<SP>1</SP>, respectively (Fig. 5), with the aid of recirculated yeasty beer and fed to the fermenting and maturing vessel A in the proportion of 3 parts malt wort to one part sugary wort. To conserve the delicate hop &c. aromas, all the required yeast production may be arranged to take place in a first vessel A and the sugary wort is then added in subsequent vessels A<SP>1</SP>, A<SP>2</SP>, A<SP>3</SP> (Fig. 6) in which no yeast is produced. In a suitable construction of fermenting and maturing vessel (Fig. 7), wort and yeast supplied through inlet connections 117, 118, respectively, is maintained in a homogeneous condition, with the avoidance of foam formation, by a rotating propeller 122 within a cylindrical shroud 123 which is adjustable with respect to the base of the vessel and one-sixth its diameter. The low-pressure conditions thereby produced assist in drawing carbon dioxide out from the fermenting and maturing liquid to an exhaust 114; fermented wort is drawn off through an outlet connection 119.